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From: David Hildenbrand <david@redhat.com>
To: Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Menzel <pmenzel+linux-kasan-dev@molgen.mpg.de>,
	Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, stable@vger.kernel.org
Subject: Re: [PATCH] mm/kasan: Don't vfree() nonexistent vm_area.
Date: Fri, 18 May 2018 18:01:02 +0200	[thread overview]
Message-ID: <6982f59e-c836-1064-c05c-a926446b6f48@redhat.com> (raw)
In-Reply-To: <784dfdf6-8fc3-be08-833b-a9097c3d1b96@redhat.com>

On 18.05.2018 17:57, David Hildenbrand wrote:
> On 01.02.2018 17:33, Andrey Ryabinin wrote:
>> KASAN uses different routines to map shadow for hot added memory and memory
>> obtained in boot process. Attempt to offline memory onlined by normal boot
>> process leads to this:
>>
>>     Trying to vfree() nonexistent vm area (000000005d3b34b9)
>>     WARNING: CPU: 2 PID: 13215 at mm/vmalloc.c:1525 __vunmap+0x147/0x190
>>
>>     Call Trace:
>>      kasan_mem_notifier+0xad/0xb9
>>      notifier_call_chain+0x166/0x260
>>      __blocking_notifier_call_chain+0xdb/0x140
>>      __offline_pages+0x96a/0xb10
>>      memory_subsys_offline+0x76/0xc0
>>      device_offline+0xb8/0x120
>>      store_mem_state+0xfa/0x120
>>      kernfs_fop_write+0x1d5/0x320
>>      __vfs_write+0xd4/0x530
>>      vfs_write+0x105/0x340
>>      SyS_write+0xb0/0x140
>>
>> Obviously we can't call vfree() to free memory that wasn't allocated via
>> vmalloc(). Use find_vm_area() to see if we can call vfree().
>>
>> Unfortunately it's a bit tricky to properly unmap and free shadow allocated
>> during boot, so we'll have to keep it. If memory will come online again
>> that shadow will be reused.
>>
> 
> While debugging kasan memory hotplug problems I am having, stumbled over
> this patch.
> 
> Couldn't we handle that via VM_KASAN like in kasan_module_alloc/free
> instead?
> 

Just realized that this will most probably not work. So please ignore my
comment for now :)

-- 

Thanks,

David / dhildenb

  reply	other threads:[~2018-05-18 16:01 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-31 16:46 Trying to vfree() nonexistent vm area (000000005d3b34b9) Paul Menzel
2018-02-01 16:33 ` [PATCH] mm/kasan: Don't vfree() nonexistent vm_area Andrey Ryabinin
2018-02-01 19:57   ` Matthew Wilcox
2018-02-01 20:22     ` Andrey Ryabinin
2018-02-02 17:20       ` Matthew Wilcox
2018-02-05  8:48         ` Andrey Ryabinin
2018-05-18 15:57   ` David Hildenbrand
2018-05-18 16:01     ` David Hildenbrand [this message]
2018-05-22 16:44   ` Andrey Ryabinin
2018-05-22 21:03     ` Andrew Morton
2018-05-23 12:33       ` Andrey Ryabinin
2018-05-26  3:31         ` [PATCH] mm-kasan-dont-vfree-nonexistent-vm_area-fix kbuild test robot
2018-05-26  3:48           ` Andrew Morton
2018-05-28  4:13             ` Ian Kent
2018-05-28  4:39               ` Ian Kent
2018-05-29  4:01                 ` Ian Kent
2018-05-30 11:53         ` kbuild test robot

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